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The utmost beauty of geometry: pulsars

by Prof. Jarosław Dyks (CAMK)

 

The lecture's subject is the radiative pulsar astrophysics. Pulsars are unusual astrophysical objects that reveal tens of enigmatic phenomena in domain of flux variability and polarization, with their spectra ranging from radio to hard gamma rays. Because of highly relativistic particles in their strongly magnetized magnetospheres, pulsar emission is extremely anisotropic and polarized, which makes the role of geometry far more complex than in typical astrophysical sources. The lack of simple symmetry, the role of quantum effects in high magnetic field, and the complexity of relativistic plasma physics furthermore contribute to the fact that the mechanisms and geometry of pulsar radiation remain unknown. The pulsar enigma persists despite that several regular patterns and plenty peculiar effects have been detected through decades of observations. Given the enormous data-to-understanding ratio, this will be a lecture on one of the biggest puzzle of contemporary astrophysics.

The lectures will present the observed radiative properties of solitary pulsars, from gamma-rays to radio. More emphasis will be put on the radio band, in which pulsars reveal astonishingly rich behaviour that includes the profile zoo, pulse modulation effects (subpulse drift, nulling, profile moding), as well as regular and peculiar polarization effects (polarization modes, variations of polarization angle, circular polarization). On theoretical side, I will introduce basics of magnetospheric theory with elements of plasma physics as required for interpreting discussed radiative effects. An introduction to polarization will be made, with practical application of Poincare sphere to observed pulsar data. Leading models for coherent radio emission processes and for the observed radio phenomenology will be described. Contemporary models for the high-energy pulsar emission will be presented (gamma-rays, X-rays), including the discussion of caustic effects in rotating magnetospheric-wide emission regions. The lectures will mostly focus on solitary (non-binary) pulsars, so the accretion will not be addressed. The emphasis on the `radiative' means that most of the pulsar timing field will not be addressed, either.

Lectures will start March, 2nd, 2021.

Schedule: Tuesdays, 11.15 am, via Zoom

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